Letoff mechanism for looms



' Feb. 17, 1942. Ni. w. PHILLIPS 2,273,474

LETOFF MECHANISM FOR LOOMS Filed Dec. 1'7, 1940 Patented Feb. 17, 1942Lnfrorr MECHANISM Fon LooMs Martin W. Phillips, Lowell, N. C., assignorto Draper'Corporation, Hopedale, Mass., a corporation of MaineApplication December 1'7, 1940, Serial No. 370,521 6 Claims. (ci.139-109) This invention pertains'to let-ofi mechanisms for looms andmore particularly relates to the positive type of let-o, wherein thewarp beam is positively rotated tofA supply the warp.

Let-offs'of the type above referred to usually comprise a warp beamgeared to a transmitting shaft, which shaft carries a pinion driven fromsuitable mechanism connected with the loom, which pinion, when connectedto the transmitting shaft, acts thereby to .transmit the required rotarymovement Vto the warp beam. Let-off mechanisms of this type positivelyrotate the I warp beam with an intermittent forward motion to let offthe Warp. The rate of let-off is controlled by mechanism connected tothe whip roll and othermechanism actuated by the variationin diameter ofthe warp sup-ply on the warp beam. I have found that by providing meansfor oscillating the warp beamiof la let-off of the positive type a moreeven and constant tension in the warp sheet is provided therebyincreasing the quality of the cloth.

Accordingly it is aprincipal object of this in vention to provide in aloom, a let-oir mechanism including a Arotatable warp beam, me-

' chanical means for positively rotatingthe warp beam in one directionto'let-off the warp and resilient means for positively rotatingr thewarp beam in the opposite direction to take up the warp, said meansacting intermittently and in succession whereby the warp beam willoscillate and `at the same time have a positive step by step rotation tolet-off the warp.

This and other'objects of the invention are accomplished by theconstruction illustrated on the accompanying drawing, of which:

Fig. 1 isa side elevation of a portion of a loom having the improvedlet-off mechanism attached thereto;

Fig. 2' is a front elevation of a portion of the mechanism shown in Fig.l; and,

Fig. 3 is a View taken on line 3-3 of Fig. 1.

The drawing shows only a part of a loom with my improved let-offmechanism attached thereto, parts of the loom not shown being of usualconstruction and forming no part of the present invention.

The improvement forming my invention is adapted to be used with any ofthe so called positive types of let-off which include a warp beam gearedto a transmitting shaft, which shaft is driven lfrom suitable mechanismconnected with the loom and in which brake means are employed to preventunintentional movement of the transmittngvshaft. Ofv` such positive`types of let-oiis, theRoper and Bartlett are the twc best known anduniversally used.

The drawing shows a portion of the rear right hand side of v`a loom. Theparts shown include a warp beam I rotatably mounted in a bearing 2attached to the right hand side frame 3 of the loom. Alsimilar bearingis provided onthe left hand side frame (not shown).

For the purpose ofillustration, the improvement ofemyinventionis shownas applied to a let-off similar tothe Bartlett type of let-oi. Thelet-oi 'may comprise a vertical worm shaft 4 havingal ratchet wheel l5fixed thereto adjacent its lower end, a hand Wheel-6 fixed theretoadjacent its upper end and a worm 'I xed thereto intermediate its ends.The Aworm shaft 4 is mounted in three vertically spaced bearings 8,

' 9 and Il! carried by a bracket II`which is attached to the side frameas at I2 andIS.

A, horizontal shaft I4 hasone end mounted in a bearing carried by abracket I5 attached to the side frame 3 and the other -endmounted in abearing I6 carried -by-the bracket II. Shaft Ill has -a worm `wheel I5on one end adapted toengage the worm 'I on worm shaft 4 and a pinion I6onthe other end adapted to engage a gear I1 xedly attached to the warpbeam I.

'Loosely mounted on worm shaft tlis a pawlzcarrier I8, having pawls I 9and 2Il mounted; thereon. A'rod 2I pivoted to the pawl carrier I'B isladapted tobe `pulledforwardly bya reciprocating link 22 to therebyrotategthe :ratchet wheel and ,worm shaft 4 in the direction to effectlet-off of the Warp sheet `from the warp beam. 'The return stroke of-rod r2I is effected vby a compression spring 23. yLink 22 may beactuated by a 4moving part of the loom (not shown).

A friction brake tohcld worm shaft 4 from unintentional movement isprovided. The fric tion brake may comprise a brake drum 24 xedly mountedon shaft# and a brake band mounted on the drum, comprising a pair ofsemi-circular members 25 and 26 pivotally connected together at one endasiatV 21 and adjustably connected together at their other ends by meansof bolt 28 and cam 29. The brake band may belined with leather 30 orothersuitable friction material.

Laterally extending from member 25 of the brake band are a pair ofspaced apart lugs 3I and 32. Extending into the space between the lugs3i and 32 is a stop or ,ange 30' formed as an integral part of bracketII. A coiled spring 33 has one end attached yto the loom frame as at 34and the other end attached to lug 3|.

`l`"lhe mechanismfior-determining the `length of the forward stroke ofrod 2| and thereby the amount of warp let off by the warp beam on eachpositive forwardly rotative movement thereof, may comprise a leverpivoted to the right hand side frame 3 as at 36. The lower end of lever35 slidingly embraces rod 2| as at 31. A collar 38 is xedly attached torod 2| forwardly of the point of connection 31 between rod 2| and lever35. Lever 35 at its upper end is pivotally con- I nected to a rod 39which in turn is pivotally connected to the lower end of an arm 4|). Arm48 is Xedly attached to a shaft 4| which is mounted in a bearing 42 on abracket 43 attached to the right hand loom side 3 as at 44. A similarbracket and bearing (not shown) supports shaft 4| on the left hand sideof the loom. A whip roll 45 is mounted in a bearing 48 on an arm 41lixedly attached to shaft 4|. A similar bearing and arm (not shown)supports the whip roll on the left hand side of the loom. A pair ofadjustable collars 48 and 49 are mounted on rod 39 for adjusting thecompression of a coiled spring 50 mounted on rod 39.

A short shaft 5| is mounted in a bearing on a bracket 52 attached to theright hand loom side frame 3 as at 53. A lever 54 carrying a roller 55at its upper end is iixedly attached to one end of shaft 5|. The roller55 is pressed against the warp supply on the warp beam by a spring (notshown). A short lever 56 is xedly attached to the other end of shaft 5|.

The upper end of lever 56 is pivotally connected to the lower end of alever 51. The upper end of lever 51 is pivotally connected to the longarm 58 of a bell crank lever which is pivotally mounted on the loom sideframe 3 as at 59. The short arm 59 of the bell crank lever slidinglyembraces the rod 39 between spring 50 and an adjustable collar 5|mounted on rod 39.-

Rod 2| is pivotally connected to the pawl carrier I8 at one end and issupported by bracket 60 at its other end. An adjustable collar 6| isxedly secured on rod 2| and a coiled compression spring 23 is mountedthereon between collar 6| and bracket 68. The link 22 actuated by amoving part of the loom (not shown) slidingly engages the rod 2|rearwardly of the collar 6|.

As the link 22 moves to the right as viewed on Fig. 1 it engages thecollar 6| and pulls the rod 2| to the right compressing the spring 23and moving the pawls I9 and 20 with the ratchet Wheel 5 to positivelyrotate the warp beam in a direction to effect let-off of the warp sheet.The amount of let-off on each positive feeding stroke of rod 2| dependsupon the position of collar 6| when engaged by the link 22. The positionof collar 6| is determined by lever 35, the lower end of which slidinglyembraces rod 2|. As the lower end of lever 35 moves to the right as seenon Fig. 1 it engages collar 38 and moves rod 2| to the right therebycausing a shorter feed stroke and a smaller let-off of warp. As thelower end of lever 35 moves to the left, the spring 23 will move the rod2| to the left until the collar 38 abuts the lever 35 and the feedingstroke will be lengthened thereby increasing the amount of let-off.

The movements of lever 35 are effected by the variation of warp tensioncaused by shedding or other means and by the variation in the diameterof the amount of warp upon the Warp beam. As the tension on the warpincreases as for instance upon the opening of the shed, the whip roll 45is moved downwardlyas seen on Fig. I, thereby moving the lower end oflever 35 to the left thereby increasing the amount of let-olf. As thediameter of the warp on the warp beam decreases the lever 54 moves tothe left as viewed on Fig. 1 causing the bell crank lever to reduce thecompression on spring 50 thereby moving the lower end of lever 35 to theleft and increasing the amount of let-off. The movement of the whip rolland the lever 54 in the opposite direction decreases the amount oflet-off.

The operation of the device is as follows:

When the rod 2| is moved to the right by link 22, the worm shaft 4 isrotated in the direction to rotate the warp beam to let-olf the warpsheet. The amount of positive motion given to the ratchet wheel by rod2| is controlled by the mechanisms previously described. When the pawlsact to turn the worm shaft 4 to let-olf the warp, the brake band willturn with shaft 4 against the pull of spring 33 until lug 3| abuts theflange 30', thereafter as shaft 4 continues to turn the brake drum willslip in the brake band.

Upon completion of the driving stroke of the pawls, the rod 2| is movedrearwardly by the compression spring 23 thereby moving the pawls intoposition for another driving stroke. At the same time the spring 33 willmove the brake band counter-clockwise as seen on Fig. 3 thereby rotatingshaft 4 and through shaft |.4 turn the warp beam in a direction to takeup the warp sheet, this motion continues until the lug 32 abuts the ange30' or until the tension of the warp equals that of spring 33 dependingupon which of these conditions occurs first.

Thus it is seen that the pawls positively turn the warp beam in onedirection with an intermittent motion and the spring 33 positively turnsthe warp beam in the opposite direction with an intermittent motion.

When the spring 33 turns the warp beam in the direction to take up thewarp, the downward pressure on the whip roll 45 is increased, therebycausing the lower end of lever 35 to move to the left, as seen onFig. 1. Thus the rotation of the warp beam by spring 33 affects theautomatic means for controlling the amount of let-olf, the effect beingto increase the amount of let-off.

As the pawls on each feeding stroke turn the worm shaft a distancegreater than the distance between the two lugs 3| and 32 and as thespring 33 can only turn the worm shaft a distance equal to the distancebetween the lugs 3| and 32 it will be seen that the positive forwardmotion of the warp beam to let-off the warp on each stroke of the pawlsis greater than the rearward motion to take up the warp caused by thespring 33 with the result that the warp beam in addition to oscillatingwill have a positive forwardly step by step rotary motion to let-off thewarp. This oscillating motion of the warp beam eliminates the necessityof a vibratory whip roll and the combined oscillating motion and thepositive forward let-off motion insures a constant even tension on thewarp sheet at all times.

By use of the device of my invention I find that it is possible toeliminate the need of a vibratory whip roll as the device will take careof the variation of warp tension caused by harness movement and willprevent binding of the warp threads.

While I have described my invention as applied to a let-oi of theBartlett type and show a particular mechanism for controlling the rateof letoff on each positive forward rotation of the warp eam it should beunderstood that my invention lis adapted to be used with any positivetype of let-off employing any suitable mechanism for controlling therate of let-off.

Having thus fully disclosed the preferred embodiment of my invention, Iclaim:

1. In a loom let-off, a warp beam rotatable to let-off Warp, ahorizontal shaft geared to said warp beam for turning same, means forrocking said shaft with a greater movement in one direction than theother, the direction of greater movement being such as to effect let-olfof the Warp whereby said warp beam is oscillated and at the same timerotated in adirection to let off Warp.

let off Warp, a horizontal shaft geared thereto,

mechanical means for moving said shaft in one direction with anintermittent motion, resilient means for moving said shaft in a reversedirection upon completion of each motion of said shaft caused by saidmechanical means, each mechanical motion being larger than eachresilient motion whereby said warp beam in addition to its oscillatingmotion is positively rotated in a directionto let off warp.

3. In a loom let-off, a Warp beam rotatable to let off warp, ahorizontal shaft geared to said warp beam, `mechanical means actuated bya moving part of the loom to positively rotate said shaft in a directionto effect let-off of the warp beam and resilient means for positivelyrotating said shaft in the opposite direction to take up warp, saidrotation to take up warp occuring after each rotation to let off warpand being of lesser amount, whereby said warp beam is oscillated and atthe same time positively rotated to let off warp.

4. In a loom let-offy a rotatable warp beam, a horizontal shaft gearedto said warp beam, a vertical shaft geared to said horizontal shaft,means for positively rotating said vertical shaft in one i directionwith an intermittent motion, a brake drum fixedly attached to saidvertical shaft, a brake band mounted on said brake drum, said brake bandhaving a pair of spaced lugs extending laterally therefrom, a stop fixedto the loom and extending into the opening between said lugs, a springconnected at one end to the loom frame and at the other end to one ofsaid lugs, said spring normally acting to turn said brake band andthereby said vertical shaft in a direction opposite to said first nameddirection.

5. In a loom let-off, a warp beam rotatable to let off warp, ahorizontal shaft geared to said warp beam, mechanical means for givingsaid shaft a positive step by step rotary motion in a forward direction,automatic means for controlling the amount of motion of each step,resilient means acting upon said shaft upon the completion of eachforward movement to turn said shaft in a reverse direction and therebyaffect said automatic means to increase the amount of forward movementof said shaft so that each forward movement of said shaft i's greaterthan each reverse movement of said shaft by an amount to insure aconstant even tension on the warp sheet at all times.

y6. In.4 a let-off for a loom including a frame having a warp beamrotatably mounted thereon, the combination of a bracket attached to theloom frame, bearings on the bracket, a vertical shaft mounted in thebearings and having a ratchet wheel xed thereto adjacent its lower endand a worm fixed thereto intermediate its ends, a. pawl carrier loselymounted on said shaft and having a pair of pawl-s, means connected to amoving part of the loom for moving said pawl carrier in one direction torotate said ratchet wheel, resilient means for moving said pawl carrierin the opposite direction, a brake drum xed to said shaft adjacent theupper end thereof, a brake band mounted on said drum and having a pairof laterally extending spaced lugs, a stop mounted on said bracket andextending between said lugs, a resilient spring having one end attachedto the loom frame and the other end attached to one of said lugs and ahorizontal shaft having a Worm Wheel on one end engaging said worm and agear on its other end engaging said warp beam.

MARTIN W. PHILLIPS.

